Not applicable.
This invention relates to conduit benders for bending electrical conduit, and in particular to a molded plastic conduit bender.
Conduit benders are well known and typically include a cast steel or aluminum alloy head and a separate handle, which may also be made out of steel, which is screwed into the head. The head has a curved shoe with a concave channel into which the conduit fits fairly closely so as to support the sides of the conduit from buckling as the conduit is being bent. The end of the conduit is hooked under a hook of the shoe and then bent in either of two ways. One way is with the conduit flat against the floor and the user rotating the handle, typically with the user""s foot on the end of the shoe which is opposite from the hook and with the user rotating the handle, so as to bend the conduit against the floor. The head typically has angle markings along the side of the shoe so that the user can approximate the angle to which the user is bending the conduit. An alternative way of bending conduit using a typical bender is to grab the handle up near the head with one hand, grab the conduit with the other hand, and place the end of the handle against the floor while bending the conduit around the shoe. Users bend the conduit in one way or the other depending upon personal preference.
Although benders such as those described are generally suitable for bending pipes and conduits, there are a number of problems associated with typical prior art conduit benders. For example, if a conduit is bent beyond a selected bend angle, the conduit can only be straightened or bent back to the selected angle by reversing the direction of bending. As the conduit bender is designed to operate only to bend the conduit in one direction, the contact surfaces on the conduit typically kink or gouge the conduit if the conduit needs to be bent backward. Under these circumstances the conduit may need to be discarded and the bend process restarted with a new length of conduit.
Furthermore, angle gauge markings can be difficult to read on prior art conduit bending devices. For example, when using the conduit xe2x80x9cagainst the floorxe2x80x9d method of bending, the angle gauge markings on the side of the head are difficult to read. When using the xe2x80x9chandle against the floorxe2x80x9d method, these marks are not positioned appropriately to determine the bend angle, and the bend angle must therefore be approximated by the user.
Another problem with prior art conduit benders is that these devices are relatively heavy, and therefore can be difficult for many users to operate. Additionally, typical conduit benders come in multiple pieces, comprising at least a separate head and a handle, and therefore require assembly prior to use. Furthermore, the handles can become disassembled from the heads during use, decreasing efficiency of bending operations. Also, typical prior art benders are constructed of conductive, typically metal, materials. As these devices are frequently used in and around electrical installations, non-conductive devices are preferable.
There remains a need, therefore, for an improved conduit bender.
The invention provides a molded plastic conduit bender, the conduit bender comprising a handle and an integrally-molded arcuate shoe portion including a channel conduit to be bent.
In one aspect, a steel hook is insert molded into the handle adjacent an end of the arcuate shoe portion, such that a conduit provided in the shoe is receivable in the hook to be bent to a selected angle. The plastic material of the bender is non-conductive, relatively lightweight, durable, and inexpensive to manufacture. The unitary construction of the handle and head also results in a very secure attachment between the handle and head, which is not prone to becoming unscrewed or detached.
To strengthen the handle during bending operations, steel tubes can also be insert molded into the handle in locations at which the user is expected to grip the handle. The steel tube is hollow such that a conduit can be slipped inside the steel tube in the handle to gain additional leverage to bend the conduit.
The invention also provides a head of a conduit bender including a plurality of sight lines extending vertically from an apex on a side of the handle. The sight lines are positioned on the handle to mark bend angles, such that an operator can look down along the handle at the shoe and gauge the amount of bend in the conduit. A second set of horizontal sight lines provided along an edge of the arcuate shoe can also be provided, to allow for gauging the bend angle when an alternate method of bending the conduit is used. Recessed numerical angle markings, molded into the handle, can provide a numerical indication of the bend angle for each set of sight lines. The numerical angle markings are both recessed and permanently marked to prevent wearing when the conduit bender is laid on a side.
The invention also provides a method and apparatus for straightening or xe2x80x9cbending backxe2x80x9d a conduit that has been bent beyond a desired angle. A first rounded saddle portion is provided on a side of the handle opposite the hook, and a second rounded saddle portion is provided on the hook. The first and second saddle portions are sized and dimensioned to receive the conduit, and are further spaced a distance apart wherein the conduit can be received between the first and second saddles. When the handle is rotated in a direction opposite the bending direction, the conduit provided between the first and second saddle portions engages, and is cradled by the two saddle portions. Further rotation of the handle in the backward direction causes the conduit to bend back. As the conduit is only contacted by the saddle portions during the bend back operation, the contact surfaces for the conduit are the rounded saddle portions which prevent kinking or damage to the conduit.
The invention also provides a hole in a molded plastic handle for a user to grab the handle adjacent to the head to facilitate bending electrical conduit in the handle against the floor method above, with the handle against the floor and the user grabbing the conduit and bending it about the head, or for carrying the bender. The molded plastic handle, being relatively wide adjacent to the head, has ample room to form a handle hole between its sides to accommodate the fingers of a user as the user grabs the handle. Preferably, the sides of the handle hole and the sides of the handle adjacent to the handle hole are radiused for the comfort of the user. This way, the user can get a firm grip on the handle when grabbing it adjacent to the head and bending the tubing about the head. The main handle and this handle may also be overmolded with an elastomer which is softer than the other plastic portions of the bender.
In another feature of the invention, one or more vice apertures are provided in the handle of the conduit bender. The apertures are sized and dimensioned to receive the conduit, wherein it is gripped in the vice apertures such that the conduit can be cut, de-burred, or otherwise modified. The vice apertures can be provided with an elastomer coating, both to improve the gripping force and to prevent damage to the conduit while held in the vice.
In another feature, the base of the head, adjacent to the tubing receiving arcuate channel, can be provided with markings on it to indicate the angle at which the tubing is bent about the head. This facilitates determining the angle of bend particularly when the second mentioned method of bending is used above, whereby the user grasps the handle adjacent to the head and grasps the tube with the other hand and bends it about the head. That way, the user does not have to strain to see the side of the shoe, but can look at the base of the shoe which he is naturally facing when bending tubing using this method.
The foregoing and other objects and advantages of the invention will appear in the detailed description which follows. In the description, reference is made to the accompanying drawings which illustrate a preferred embodiment of the invention.